Just saw your post.  Still going through the book - about ⅔ of the way through.  I'm not exactly the fastest English reader (Japanese, on the other hand, I can read rather quickly) and until I got myself a Paperwhite last month, I was barely reading any since my eyes would get tired really quickly reading books on iPad. 
  
So far, I like it, but took a bit to get going since it was difficult to figure out what was going on for a while.